﻿#include <iostream>
#include <vector>
#include <map>
#include <string>
#include <cmath>
using namespace std;

int main() {
	vector<int> primes{ 2, 3, 5, 7, 11, 13, 17, 19, 23, 29, 31, 37, 41, 43, 47, 53, 59, 61, 67, 71, 73, 79, 83, 89, 97, 101, 103, 107, 109, 113, 127, 131, 137, 139, 149, 151, 157, 163, 167, 173, 179, 181, 191, 193, 197, 199, 211, 223, 227, 229, 233, 239, 241, 251, 257, 263, 269, 271, 277, 281, 283, 293, 307, 311, 313, 317, 331, 337, 347, 349, 353, 359, 367, 373, 379, 383, 389, 397, 401, 409, 419, 421, 431, 433, 439, 443, 449, 457, 461, 463, 467, 479, 487, 491, 499, 503, 509, 521, 523, 541, 547, 557, 563, 569, 571, 577, 587, 593, 599, 601, 607, 613, 617, 619, 631, 641, 643, 647, 653, 659, 661, 673, 677, 683, 691, 701, 709, 719, 727, 733, 739, 743, 751, 757, 761, 769, 773, 787, 797, 809, 811, 821, 823, 827, 829, 839, 853, 857, 859, 863, 877, 881, 883, 887, 907, 911, 919, 929, 937, 941, 947, 953, 967, 971, 977, 983, 991, 997 };
	map<string, int> ref;
	ref["zero"] = 0;
	ref["one"] = 1;
	ref["two"] = 2;
	ref["three"] = 3;
	ref["four"] = 4;
	ref["five"] = 5;
	ref["six"] = 6;
	ref["seven"] = 7;
	ref["eight"] = 8;
	ref["nine"] = 9;
	string numstr;
	getline(cin, numstr);
	int num = 0;
	int digit = 1;
	string temp;
	for (char u : numstr) {
		if (u != ' ') temp += u;
		else {
			if (ref.count(temp) == 0) {
				cout << "Wrong input";
				return 0;
			}
			num += ref[temp] * pow(10, 3-digit);
			digit += 1;
			temp.clear();
		}
	}
	if (num < 100) {
		cout << "Wrong input";
		return 0;
	}
	int l = 0;
	int r = primes.size();
	while (r - l > 1) {
		int m = (r + l) / 2;
		if (primes[m] > num) r = m;
		else l = m;
	}
	if (primes[r] - num > num - primes[l]) cout << primes[l];
	else cout << primes[r];
	return 0;
 }


